1. Field of the Invention
The present invention relates to a radio receiver and, more specifically, to a radio receiver which receives a digital-modulated signal to produce received data through an analog-to-digital converter.
2. Description of the Related Art
In general, a radio receiver such as a pager employs an intermittent receiving scheme so as to save the battery power. Further, there has been proposed a system which can stop supplying main clock pulses to a CPU during each receiving period to stabilize the radio receiving characteristics. In Japanese Patent Unexamined Publication No. 7-99680, for example, a portable data processing apparatus is provided with an I/O slot into which a radio pager can be detachably connected. When the radio pager is receiving a radio signal, the radio pager outputs a control signal to the data processing apparatus, and thereby the main clock signal supplied to the CPU of the data processing apparatus is stopped or switched to a sub clock signal of a lower frequency during the receiving period so as to avoid causing the harmonics of the main clock to influence the radio receiving characteristics. After the receiving operation is completed, the main clock signal is supplied to the CPU and thereby the CPU starts performing data processing of the received data.